Wetting agent concentrate for agricultural chemicals

ABSTRACT

This invention relates to a stable wetting agent concentrate suitable for combination with an agrichemical which comprises a mixture of (a) a N--C 8  to C 18  alkyl lactam having from 4 to 6 carbon atoms in the heterocyclic ring and (b) a polyalkyleneoxide/polydimethyl siloxane copolymer, combined in a weight ratio of between about 10:90 and about 90:10 (a) to (b), and (c) between about 0.01 and about 25 wt.% based on total composition of an anionic surfactant, which composition exhibits synergistic wetting properties and allows for the use of lower effective dosages of the agrichemical due to induced cuticular and stomatical absorption by the plant species. The invention also pertains to the preparation of the wetting concentrate and its combination with an active component for use on a plant as a single phase composition.

BACKGROUND OF THE INVENTION

Wetting agents are an important part of agricultural chemicalformulations, since they assure uniform distribution and efficientfunctioning of the active ingredient in a composition. For example,plant surfaces are typically hydrophobic and resist wetting by aqueoussprays, thereby reducing efficient deposition of the active chemical.Many different products are available for use as wetting agentsincluding anionic, cationic, amphoteric and non-ionic types whichsuggest the wide chemical diversity and tendency for certain surfactantformulations to be optimum for certain active chemicals. In addition,specific interactions of various wetting agents with a specific activecomponent can result in widely divergent responses so that selection ofa highly effective wetting agent becomes difficult.

Selection of an appropriate and acceptable wetting agent often dependson the concentration of active material that the surfactant will acceptand ecological limitations on the amount of active chemical that can besafely dispersed into the atmosphere. As a result of theseconsiderations, certain active chemicals showing a degree of toxicity donot enjoy wide spread use since large amounts must be employed toeffectively saturate the plant and undesirable amounts are dispersed tothe atmosphere due to the inability of the wetting agent to retain arequired dosage on the plant when using a normal volume of spray.Consequently, the search for economical wetting agents and theirformulations, usable at low concentrations which provide enhancedagricultural chemical activity by improved wetting effectiveness, isongoing.

Accordingly it is an object of this invention to provide an improvedwetting agent composition which is a vehicle for the simultaneouscuticular and stomatic absorption of an agricultural chemical by aplant.

Another object of the invention is to provide a wetting agent havingsuperior absorption capability by a plant which allows for theformulation of an effective agrichemical containing significantly lowerdosages of the active chemical for treating plants.

Another object of the invention is to provide an economical andefficient wetting agent concentrate suitable for use with anagrichemical as a single phase aqueous solution.

These and other objects of the invention will become apparent form thefollowing description and disclosure.

THE INVENTION

In accordance with this invention there is provided an improved watersoluble concentrate having superior wetting properties for use incombination with an agriculturally active chemical or a formulationthereof. The present concentrate is an aqueous mixture of (a) a N--C₈ toC₁₈ alkyl lactam having from 4 to 6 carbon atoms in the heterocyclicring and (b) a polyalkyleneoxide/polydimethylsiloxane copolymer having anumber average molecular weight of from about 1,000 to about 1,000,000,combined in a weight ratio of between about 10:90 and about 90:10 (a) to(b) and (c) between about 0.01 and about 25 wt.% based on totalcomposition of an anionic surfactant.

The above concentrate, containing between about 10 and about 50 wt.%water, preferably between about 20 and about 40 wt.% water, can becombined with a desired amount of active component in a solid or liquidstate or the concentrate can be added to and mixed with the finalformulation of the active component which has been diluted with water toa recommended concentration suitable for application to a plant.Addition of the concentrate to the final formulation suitable forspraying crops produces a single phase aqueous solution which eliminatesnozzle clogging and problems associated with heterogeneous plant sprayformulations, notably nonuniform distribution of the active component.Further, since the present wetting composition provides both cuticularand stomatal absorption by the plant and hence the active ingredient,somewhat lower dosages of the active component can be used to accomplishthe desired result. This dual absorption feature is particularlybeneficial when using ecologically objectionable herbicides whosetoxicity prohibits high concentrations needed for efficacy in weed orcrop spraying. A wide range of water soluble and water insolublebiologically active components are contemplated for use in the presentinvention, including pesticides, fungicides, herbicides, plant growthregulants, biocides, leaf defoliants and the like which may be in aliquid or finely divided granulated state. Examples of suitable activecomponents includealpha-cyano-3-phenoxybenzyl-dichlorovinyl-2,2-dimethyl cyclopropanecarboxylate, 3,6-dichloro-o-anisic acid, ethyl 2-[[[[(4-chloro-6-methoxypyrimidin-2-yl) amino] carbonyl] amino] sulfonyl] benzoate (CLASSIC™),methyl 3-[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino]carbonyl]amino]sulfonyl]-2-thiophenecarboxylate (PINNACLE™),5-ethyoxy-3-trichloromethyl-1,2,4-thiadiazole, tetramethyl thiuramdisulfide, 0-ethyl-S,S-diphenyl-dithiophosphate,0,0-dimethyl-0-(4-m-tolyl) phosphorothioate, (2-chloroethyl) phosphonicacid, 4-[(acetamino)methyl]-2-chloro-N(2,6-di-ethylphenyl acetamide,chloroethyl phosphonic acid and others named on pages 9-15 of copendingpatent application, Ser. No. 07/975,811, filed Nov. 13, 1992 by KolaziNarayanan.

Component (a) in the above concentrate includes N-- C₈ to C₁₈ alkylpyrrolidones, N-- C₈ to C₁₈ alkyl caprolactams and mono- or di- methylsubstituted species of these lactams. The preferred lactams are the N--C₈ to C₁₂ alkyl pyrrolidones which may be employed individually or inadmixture, particularly N-- C₈ alone or mixtures of N-- C₈ alkylpyrrolidone with N-- C₁₂ alkyl pyrrolidone. When lactam mixtures areemployed, between about 10 and about 90 wt.% of either species can beemployed; although mixtures containing 40 to 60 wt.% of one species isparticularly recommended. AGROSOLVE®, supplied by InternationalSpecialty Products is a commercially available lactam mixture suitablyemployed in the present concentrate. When using a long chain lactamhaving more than 8 carbon atoms in the N-alkyl group, it is helpful toinclude a N-- C₁ alkyl lactam, preferably N-methyl pyrrolidone, in theconcentrate mixture to aide in solubilizing the higher lactam species.However, this solubilizer can be omitted, since after final dilution,i.e. the spray product, the higher lactams become soluble. Whenemployed, the concentration of the N-methyl lactam can vary betweenabout 0.1 and about 1.5 parts per part of total lactam.

The polyalkylene oxide/polydialkyl siloxane copolymer employed in thepresent concentrate generally contains between about 10 and about 80wt.% polyalkylene oxide, preferably polyethyleneoxide and the copolymermore desirably has a number average molecular weight of between about50,000 and about 100,000. Such copolymers are commercially available,e.g. as SILWET™ L77, L7001 and L7631, supplied by Union Carbide Corp.

The siloxane copolymers of the present invention are those containingunits of ##STR1## wherein R is hydrogen or C₁ to ₄ alkyl, preferablymethyl or ethyl; R' and R" are both lower alkyl. The most preferredcopolymer is the polyethyleneoxide/polydimethylsiloxane in about 50:50parts by weight ratio; although suitable weight ratios of lactam tosiloxane copolymer can vary between about 10:90 and 90:10, moredesirably between about 25:75 and about 75:25, a ratio of 45:55-55:45 isparticularly recommended for good results.

As stated above, the concentrate also contains up to 25 wt.% of ananionic surfactant, more desirably 10-15 wt.%, based on the totalcomposition. Suitable surfactants include sodium and potassium salts ofsulfonates, sulfates, carboxylates, phosphates and phosphonates,ammonium or alkylammonium salts and alkanol ammonium salts.

Representative examples of suitable anionic surfactants are sodiumdodecyl sulfate, alkoxylated C₁₀ to C₁₄ phosphate esters, C₆ to C₁₈alkyl phosphates, sodium naphthalene sulfonate, lithium alkarylsulfonates, sodium alkylbenzene sulfonates, alkyl tristyrylphosphate,sodium, potassium and ammonium triethanol amine salts of the above.Sodium C₈ to C₁₂ alkyl sulfates are particularly recommended for theirhigh surfactant properties with respect to the lactam.

The concentrates of the present invention can be combined with theactive component before or after formulation with other additives orbefore or after dilution of the formulation with water for use onplants. The final spray product formulation contains between about 0.05and about 0.5 wt.%, preferably between about 0.1 and about 0.3 wt.% ofthe concentrate which is thoroughly mixed until a homogeneous, singlephase aqueous solution is obtained.

The wetting compositions of the present invention are unique in thatthey possess synergistic properties which far exceed the beneficialeffects achieved or expected with the higher alkyl pyrrolidones or thepolyalkyleneoxide/polydimethylsiloxane copolymers alone. It is foundthat the mixture of these components performed unexpectedly better thanthe individual components at the same wetting agent concentration level,as shown below. More specifically, the wetting and spreading time of theaqueous formulations containing between about 0.05 and about 0.5 wt.%,preferably between about 0.1 and about 0.3 wt.%, of the presentconcentrate achieves a two to four fold reduction in wetting time overthat obtained with similar formulations containing only the lactam orthe copolymer. Further, the dual mode of plant uptake allows for moreefficient use of the active component and permits a reduction in theamount needed to achieve desired results. Normally, between about 50-90%of a pesticidal or herbicidal spray is lost to the atmosphere, soil andground water during commercial dusting or spraying. Use of the presentconcentrate solves this problem by effecting immediate dual absorptionof the active chemical which is combined with the wetting agent in thecomposition. Hence, many of the effective pesticides and herbicides,which have been judged too toxic for general use in the treatment ofplants, can now safely be made available. The long chain alkyl lactamsof the present compositions are found to enhance the biological activityof the active component when the above concentration levels aremaintained; whereas the silicone components, which have a low contactangle, promote the spreading of the bioactive compound and may beeffectively incorporated at lower concentrations.

Having generally described the invention, reference is now had to thefollowing examples which provide preferred and comparative examples;however, the examples are not to be construed as limiting to the scopeof the present invention as set forth above and in the appended claims.

EXAMPLES 1-8

The following compositions were prepared. The components of Examples 3and 4-8 were mixed in a glass beaker for 30 minutes at room temperatureuntil a homogeneous liquid was obtained.

EXAMPLE 1

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            0.0                                                           N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            0.0                                                           Silwet L-77     100.0                                                         Water           0.0                                                           Total           100.0                                                         ______________________________________                                    

EXAMPLE 2

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            100.0                                                         N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            0.0                                                           Silwet L-77     0.0                                                           Water           0.0                                                           Total           100.0                                                         ______________________________________                                    

EXAMPLE 3

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            50.0                                                          N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            0.0                                                           Silwet L-77     50.0                                                          Water           0.0                                                           Total           100.0                                                         ______________________________________                                    

EXAMPLE 4

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            75.0                                                          N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            0.0                                                           Silwet L-77     25.0                                                          Water           0.0                                                           Total           100.0                                                         ______________________________________                                    

EXAMPLE 5

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            53.7                                                          N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            13.4                                                          Silwet L-77     0.0                                                           Water           32.9                                                          Total           100.0                                                         ______________________________________                                    

EXAMPLE 6

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            40.3                                                          N-Methylpyrrolidone                                                                           0.0                                                           N-Dodecylpyrrolidone                                                                          0.0                                                           Na Lauryl SO.sub.4                                                                            13.4                                                          Silwet L-77     13.4                                                          Water           32.9                                                          Total           100.0                                                         ______________________________________                                    

EXAMPLE 7

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            20.2                                                          N-Methylpyrrolidone                                                                           20.2                                                          N-Dodecylpyrrolidone                                                                          13.2                                                          Na Lauryl SO.sub.4                                                                            13.5                                                          Silwet L-77     0.0                                                           Water           32.9                                                          Total           100.0                                                         ______________________________________                                    

EXAMPLE 8

    ______________________________________                                        Component       Percent Composition                                           ______________________________________                                        N-Octylpyrrolidone                                                                            16.2                                                          N-Methylpyrrolidone                                                                           16.2                                                          N-Dodecylpyrrolidone                                                                          10.6                                                          Na Lauryl SO.sub.4                                                                            10.8                                                          Silwet L-77     20.0                                                          Water           26.4                                                          Total           100.0                                                         ______________________________________                                    

EXAMPLE 9

A modified Drave's wetting test*, was carried out on the compositions ofeach of the above examples after they had been diluted with water(reported in Table I) to simulate concentrations employed in commercialspray compositions.

The wetting target was a 0.7 g. cotton skein and a 0.9 g. weight wassuspended from the bottom of the cotton skein.

Comparisons were made between the present compositions, Examples 3-5 and7) commercial wetting agents Silwet L-77 (Example 1) andN-octylpyrrolidone (Example 2) were made and wetting properties areshown in Table I. The wetting times (Average time in seconds required tosink the cotton skein) are shown as a function of concentrations inTable I.

                  TABLE I                                                         ______________________________________                                                  Sinking                                                                       Time (seconds)    Visual                                            % Conc.     Avg    SD           Appearance                                    ______________________________________                                        Composition of Example 1                                                      0.503       3.6    0.6          cloudy                                        0.300       4.7    0.6          cloudy                                        0.250       5.5    0.4          cloudy                                        0.199       6.6    0.6          cloudy                                        0.145       8.2    0.9          cloudy                                        0.101       10.8   0.7          hazy                                          0.075       16.8   1.2          hazy                                          0.049       23.7   3.0          hazy                                          Composition of Example 2                                                      0.500       <1.5   --           cloudy                                        0.300       <1.5   --           cloudy                                        0.250       <1.5   --           cloudy                                        0.200       <1.5   --           cloudy                                        0.150       <1.5   --           hazy                                          0.102       5.5    0.7          clear                                         0.075       62.1   18.0         clear                                         0.052       714.4  174.8        clear                                         Composition of Example 3                                                      0.500       <1.5   --           cloudy                                        0.302       <1.5   --           cloudy                                        0.253       2.7    0.2          cloudy                                        0.200       4.3    0.4          cloudy                                        0.151       6.1    0.6          cloudy                                        0.101       12.7   0.7          hazy                                          0.075       15.4   2.1          hazy                                          0.050       31.9   2.4          slightly hazy                                 Composition of Example 4                                                      0.504       <1.5   --           cloudy                                        0.301       <1.5   --           cloudy                                        0.251       <1.5   --           cloudy                                        0.201       <1.5   --           cloudy                                        0.153       <1.5   --           hazy                                          0.104       9.2    0.4          clear                                         0.076       22.6   1.7          clear                                         0.050       94.3   27.3         clear                                         Composition of Example 5                                                      0.500       <1.5   --           clear                                         0.300       <1.5   --           clear                                         0.251       <1.5   --           clear                                         0.200       <1.5   --           clear                                         0.152       4.8    0.6          clear                                         0.103       9.0    0.6          clear                                         0.074       24.5   3.5          clear                                         0.049       702.3  354.9        clear                                         Composition of Example 6                                                      0.500       <1.5   --           clear                                         0.302       <1.5   --           clear                                         0.252       <1.5   --           clear                                         0.201       3.4    0.5          clear                                         0.152       5.8    0.5          clear                                         0.102       12.1   1.0          clear                                         0.075       24.3   4.2          clear                                         0.050       183.0  84.1         clear                                         Composition of Example 7                                                      0.503       <1.5   --           clear                                         0.300       3.0    0.4          clear                                         0.253       5.0    0.7          clear                                         0.200       6.6    0.8          clear                                         0.150       12.3   1.1          clear                                         0.100       24.2   3.5          clear                                         0.075       54.0   10.0         clear                                         0.050       577.8  196.1        clear                                         Composition of Example 8                                                      0.500       <1.5   --           clear                                         0.300       3.2    0.6          clear                                         0.251       4.0    0.9          clear                                         0.200       6.3    0.3          clear                                         0.150       8.9    0.6          clear                                         0.101       19.0   1.7          clear                                         0.075       32.5   8.1          clear                                         0.051       77.1   21.3         clear                                         ______________________________________                                    

EXAMPLE 10

The following compositions shown in Table II were prepared as spraysolutions and compared.

                  TABLE II                                                        ______________________________________                                        Composition (a) Blank                                                         PINNACLE 25 DF        0.25 oz. (7 g.)                                         CLASSIC 25 DF         0.25 oz. (7 g.)                                         Water                 20 gallons                                              Composition (b)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 15 DF         0.25 oz (7 g.)                                          Concentrate of Example 6                                                                            75 g.                                                   Water                 20 gallons                                              Composition (c)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 24 DF         0.25 oz (7 g.)                                          Concentrate of Example 6                                                                            150 g.                                                  Water                 20 gallons                                              Composition (d)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          Concentrate of Example 6                                                                            375 g.                                                  Water                 20 gallons                                              Composition (e)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          Concentrate of Example 5                                                                            75 g.                                                   Water                 20 gallons                                              Composition (f)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          Concentrate of Example 5                                                                            150 g.                                                  Water                 20 gallons                                              Composition (g)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          Concnetrate of Example 5                                                                            375 g.                                                  Water                 20 gallons                                              Composition (h)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          SILWETT L 77          77 g.                                                   Water                 20 gallons                                              Composition (i)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          SILWETT L 77          150 g.                                                  Water                 20 gallons                                              Composition (j)                                                               PINNACLE 25 DF        0.25 oz (7 g.)                                          CLASSIC 25 DF         0.25 oz (7 g.)                                          SILWETT L 77          375 g.                                                  Water                 20 gallons                                              ______________________________________                                    

EXAMPLE 11

The compositions prepared above in Table II were subjected to biologicalfield tests during clear weather at 50% humidity, low wind velocity and80° F. temperature. A sprayer equipped with a 10 inch nozzle Teejet tipoperated at 35 psi pressure was operated at a rate of 20 gals/acre ofherbicide. The plants tested, in a 45×10 foot plot, had about 5 inchgrowth. Three replicates of each plant was sprayed and, 18 days afterspraying, the results were catagorized as to broadleaf* control andsoybean injury. The results of these tests are reported in followingTable III.

                  TABLE III                                                       ______________________________________                                        Spray Composition                                                                         % Broadleaf Control                                                                           % Soybean Injury                                  ______________________________________                                        (a)          50*            3                                                 (b)         65              0                                                             60              0                                                             80              5                                                 (c)         70              5                                                             75              5                                                             75              5                                                 (d)         80              10                                                            80              10                                                            95              5                                                 (e)         70              5                                                             60              5                                                             40              0                                                 (f)         72              5                                                             65              5                                                             70              5                                                 (g)         70              5                                                             65              0                                                             65              5                                                 (h)         60              8                                                 (i)         66              10                                                (j)          77*            15                                                ______________________________________                                         *estimated value                                                         

What is claimed is:
 1. An aqueous agricultural chemical solutioncontaining between about 0.05 and about 1.0 weight % of a clear,homogeneous wetting agent concentrate consisting essentially of:(a) aN-- C₈ to C₁₈ alkyl lactam having from 4 to 6 carbon atoms in aheterocyclic ring; (b) a polyalkyleneoxide/polydimethylsiloxanecopolymer combined in a weight ratio of between about 10:90 and about90:10 lactam (a) to copolymer (b) and (c) between about 0.01 and about25 wt.% based on total composition of an anionic surfactant.
 2. Theconcentrate of claim 1 wherein said copolymer is combined in a weightratio of between about 25:75 and about 75:25.
 3. The concentrate ofclaim 1 wherein said lactam is a N-- C₈ to C₁₂ alkyl pyrrolidone.
 4. Theconcentrate of claim 3 wherein said lactam is N-- C₈ alkyl pyrrolidone.5. The concentrate of claim 3 wherein said lactam is a mixture of a N--C₈ alkyl pyrrolidone and a N-- C₁₂ alkyl pyrrolidone.
 6. The concentrateof claim 1 wherein said copolymer has a number average molecular weightof from about 50,000 and about 100,000.
 7. The concentrate of claim 1wherein said anionic surfactant is an alkali metal salt of a C₆ to C₁₈alkyl sulfate.
 8. The concentrate of claim 7 wherein said surfactant issodium lauryl sulfate.
 9. The concentrate of claim 1 in admixture withan effective plant altering amount of an agriculturally active compound.10. The solution of claim 1 wherein said aqueous solution is a watersolution and the concentrate is present in water at a concentration ofbetween about 0.1 and about 0.3 wt.%.
 11. The concentrate of claim 1wherein the lactam (a) component contains a N-alkyl group having morethan 8 carbon atoms and wherein the concentrate contains between about0.1 and about 1.5 parts of N-methyl lactam per part of total lactam. 12.The concentrate of claim 11 wherein the concentrate contains betweenabout 0.3 and about 1 part of N-methyl lactam per part of total lactam.13. The concentrate of claim 11 wherein (a) contains N-dodecylpyrrolidone.